The present invention relates to an oscillating scanhead drive for use with medical diagnostic ultrasound equipment. In particular, the invention relates to a drive for a scanhead of the type used in an ultrasound sector scanner.
There are numerous types of ultrasound sector scanners presently used for medical diagnosis. These scanners employ two basic types of apparatus to impart mechanical movement. In the first type of apparatus, from two to four transducers are mounted on a rotating armature, and an individual one of these transducers is activated for transmission and reception of ultrasound energy at any given time. This type of scanhead, typically called a "rotary" scanhead, while in common use, is very expensive to produce for a number reasons. In particular, each of the transducers used in the scanhead must be matched to the other transducers in order to avoid flickering or degradation of image quality when the unit switches from one transducer to the next one. Accordingly, hand matching of transducers, a labor intensive, expensive procedure, is employed to select matched transducers to be mounted in a rotor. Then, once matched transducers are obtained, it is critical to mount them all on the same axis on the rotating armature in order to avoid problems of image flicker on the screen as the different transducers are activated.
In another type of ultrasound scanhead called an "oscillating" scanhead or a "wobbler", a single transducer is used. That transducer is mounted in a mechanism which oscillates back and forth. The oscillating scanhead has the advantage of being less expensive to produce in that only a single transducer is required, thereby avoiding the problems associated with matching transducers and aligning them on the same axis. A problem, however, with oscillating scanheads is that they typically vibrate quite a bit due to their oscillatory operation. Accordingly, it would be highly desirable to have an oscillating mechanism which is always dynamically balanced.